The present invention relates in general to a process and apparatus for reduction or elimination of vibrations in shipboard liquid-lubricated air compressor systems and, more particularly, to a process and apparatus which reduce or eliminate pulsations, vibrations and noise in the air piping on the discharge side of water-injected rotary positive displacement screw type air compressors.
Rotary positive displacement single screw compressors may be used to produce high air discharge pressures ranging to about 3,000-5,000 lbs./in..sup.2. In these compressors, the main components are a threaded main rotor and one or more gate rotors having teeth which mesh with the teeth on the main rotor. The main rotor is in a closely fitting housing having ports for the admission and discharge of gases and liquids. The compression process begins when gases are drawn into a rotor thread that is open to the suction plenum. After the thread has been filled, a gate rotor tooth rotates into position to close off the thread from the suction plenum. As the main rotor continues to turn, it decreases the volume of the thread which compresses the trapped gases.
During this process, copious amounts of liquid such as water are injected to seal the clearances between the main rotor and housing, main rotor and gate rotor, gate rotor and housing, and main rotor and discharge port. When the desired discharge pressure is reached, the main rotor thread uncovers a discharge port, and the high pressure air/water mixture is discharged through the port to a discharge plenum or discharge line. This process occurs simultaneously on both sides of the compressor main rotor to balance compression forces. However, these high pressure discharges contain alternating phases of air and liquid of differing densities that create a pulsating flow that results in high vibration levels in the downstream piping.
It is known to use tuyere-type centrifugal separators having a plurality of vanes as separators to remove liquids and solids from gases. The vanes impart a centrifugal motion that directs the entrained liquid and solid particles to the periphery of the shell or housing. From there the separated particles and liquid can be drained into a sump. It is known to use such centrifugal-tuyere separators for steam service downstream of steam engines for removal of condensate and for air service to remove liquid from air between stages and downstream of the compressor.